This invention relates generally to pipe couplings, and more specifically to couplings characterized as speeding the repair of underground piping systems as commonly used in the irrigation of avocado and citrus groves.
Such systems generally comprise a number of twenty-foot lengths of plastic pipe extending horizontally in rows, which are usually spaced about twenty feet apart. The lengths of pipe in each row are usually connected to each other by a pipe tee, to which is attached a vertical length of pipe commonly called a riser. The horizontal rows of pipe are usually buried twelve to eighteen inches below the ground surface with the vertical length of pipe or riser extending some distance above the ground. A sprinkler head is attached to the upper end of the riser and serves to distribute water around an adjacent tree.
Citrus and avocado groves usually have about ninety trees per acre of ground, and since each tree has its own sprinkler, it is clear that each grove acre would have at least about 1800 feet of underground piping. Also, since the lengths of pipe are connected by a pipe tee, there are approximately 270 glued, or cemented, underground connections per acre. This type of underground irrigation system, over a period of time, is subject to damage of various kinds which must be repaired.
Probably the most common damage is caused by roots of trees in the grove. As such trees mature, their roots become quite massive and they often press against the underground pipes with sufficient force to crack or break them. Heavy rains occasionally cause earth movement which can cause stresses in the piping sufficient to cause some of the glued connections to loosen and leak and therefore necessitate repair. Also, grove workers, grove machinery and even burrowing animals may occasionally damage the underground piping.
The repair of underground piping in a grove is made particularly difficult by the tree roots, many of which must be severed before the damaged pipe section can be replaced. Heretofore, it has been necessary to uncover many feet of pipe on each side of the damaged section to provide sufficient pipe flexibility to permit re-connection of the pipe ends after the damaged section had been repaired. The excavation of a trench of sufficient length to permit pipe upward flexing for repair was difficult, time consuming, and expensive in terms of labor cost.
It should be pointed out that the flexing of the pipe and insertion of the pipe end into the standard pipe collar for re-connection had to be accomplished within a few seconds after the glue or cement had been applied to the pipe end. Otherwise, the pipe end would not enter the coupling, as commercial grades of plastic pipe cement are quick setting compounds. Consequently, the re-connecting manuever was never easy.